Air-brake.



PATENTED APR. 5, 1904.

D. DUNN.

AIR BRAKE.

APPLICATION FILED 1mm 23, was.

NO MODEL.

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UNTTED STATES Patented April 5, 1904.

PATE T OFFICE.

HALF TO JAMES H. PROSSER, OF MAHANOY CITY, PENNSYLVANIA.

AIR-BRAKE.

SPECIFICATION forming part of Letters Patent No. 756,604, dated April 5, 1904.

Application filed June 23, 1903. Serial No. 162,710- (No model.)

T0 at whom, it may concern:

Be it known that I, DENNIS DUNN, a citizen of the United States, residing at Mahanoy City, in the county of Schuylkill and State of Pennsylvania, have invented a new and useful Improvement in Air-Brakes, of which the following is a specification.

My invention relates to air-brakes used on railway-cars. It consists of means for recharging the ordinary auxiliary reservoir while the brakes are engaged or for gradually recharging such reservoir while brake-pressure is being decreased.

It further consists of novel features of construction, all as will be hereinafter fully set forth.

The drawing represents a partial vertical section and partial elevation of a well-known form of triple valve providedwith a device embodying my invention.

Referring to the drawing, 1 designates the ordinary train-pipe leading from the compressor or the main drum on the engine under the train and to a triple valve 2 on any car. A branch pipe 3 leads from train-pipe 1 to the upper part of an auxiliary cylinder 4, in which reciprocates a piston 5. The cylinder is divided by a transverse partition 6 into two chambers 7 and 8. The end of the piston 5 passes through a stuiiing-box 10 in the partition 6 and carries at its lower end a valve 11, adapted to seat in the head 12 of the cylinder.

The chamber 7 of the cylinder Lis connected to the main pipe 1 below the piston 5 by two branch pipes 13 and 14:. In the pipe 18 is a valve 15, normally seated by a spring 16 and adapted to be unseated by an excess of train-pipe pressure. The other pipe, 14, has a valve 17 seated by a spring 18 and unseatable by excess of pressure in the chamber 7. A stop 19 in the cylinder 'iprev'ents the piston 5 being forced down to the port of the pipes 13 14, the piston being normally raised by a spring 20. A pipe 21 leads from the brake cylinder discharge or air exit (not shown) to the lower chamber 8 of the cylinder 4.

As the driver-brake triple valve which I have chosen as the form to be illustrated in connection with my device is well known and forms no part'of my invention, I will not describe it except as it is necessary to show the working of my device. For like reasons I have omitted from the drawing the brake-cylinder on the car and all the parts of the device attached to the engine.

The operation is as follows: We will assume that the train is running, brakes off, that train pipe pressure stands at seventy pounds, and that my device stands at the position shown. To apply the brakes, the engineer may exhaust ten pounds from train-pipe, leaving pressure at sixty pounds. The piston 22 of the triple valve will then be forced down by the excess pressure in the auxiliary reservoir. (Not shown.) This permits pressure to flow to the brake-cylinder through port 23, producing a pressure there of, say, twenty-five pounds and applying the brakes. As chamber 8 of my device is connected with brake-cylinder, the pressure of twenty-five pounds will be communicated thereto. We will assume that the area of piston 5 is three square inches and that the effective area of valve 11 is one square inch. (In practice allowance must be made for the thrust of the spring 20.) The excess pressure on the under side of piston 5 is thirty pounds, and the pressure on the valve 11, tending to lower piston, will be twenty five pounds. If then the engineer desires to gradually recharge the auxiliary reservoir, he may increase train pipe pressure two pounds to square inch or to sixty-two pounds'in all. If the area of piston 5 is three square inches, there will be exerted six pounds additional force on the upper side of piston 5,which, with the twenty-five pounds pressure on the valve 11, will make a total of thirty-one pounds or an excess of one pound to raise main valvepiston 22 to lower piston 5 and to open valve 11. The raising of piston 22 permits the recharging of the auxiliary reservoir to, say, sixty-two pounds if this pressure is maintained in main drum. Of course the lowering of piston 5 and valve 11 has permitted a slight exhaust from the brake-cylinder; but this ceases when one pound has been exhausted, leaving twenty-four pounds, or practically full pressure, in brake-cylinder. When brakes are removed and train-pipe pressure is run up to normalsay seventy poundsthe piston 5 is temporarily depressed without effect, as there is no pressure on brake-cylinder. The spring 16 has, however, a force of, say, three pounds, so that the valve opens and the pressure on both sides of piston 5 nearly equalizes, permitting the spring 20 to raise the piston and to seat the valve 11. As the spring 18, controlling the valve 17 has a force of, say, twenty pounds, the valve will operate only when there is a great difference in cylinder and train-pipe pressures to relieve the chamber 7 below the piston 5.

It will be seen that the efiectof my device is to permit a gradual increase of air-pressure in the auxiliary reservoir while pressure in the air-brake cylinder is being gradually decreased.

It will be evident that various changes may be made by those skilled in the art which will come within the scope of my invention, and I do not, therefore, desire to be limited in every instance to the exact construction herein shown and described.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. An auxiliary air-brake device comprising a cylinder, a piston in said cylinder, a valve controlling the exhaust from the brake-cylinder connected to said piston, pipes connecting each end of said cylinder with the train-pipe and a valve in one of said pipes adapted to be seated by excess pressure in said cylinder, whereby exhaust from the brake-cylinder is controlled by variation in train-pipe pressure.

2. An auxiliary air-brake device comprising a cylinder, a piston in said cylinder, a chamber adjacent said cylinder, a pipe leading from the brake exhaust-port of the triple valve to said chamber, a valve controlling the exit from said chamber connected to said piston, a pipe connecting the end of said cylinder nearer said valve with the train-pipe, a valve in said pipe adapted to be seated by excess pressure in said cylinder and a normally unobstructed pipe connecting the other end of said cylinder with the train-pipe, whereby exhaust from the brakecylinder is controlled by variations in trainplpe pressure.

3. In an air-brake system, an auxiliary cylinder on a car connected to train-pipe at both sides of its piston, one of such connections being valved and means connected with said piston for operating a brake-cylinder exhaustvalve.

4. In an air-brake system, an auxiliary cylinder on a car, a piston in said cylinder, a rod connecting said piston with a brake-cylinder exhaust-valve, a valved train-pipe connection with said cylinder at the side of said piston nearer said valve and a free train-pipe connection with said cylinder at the other side of said piston, whereby said exhaust-valve is operated by variations of train-pipe pressure.

5. An auxiliary air-brake device comprising a cylinder, a piston in said cylinder operatively connected to a brake-cylinder exhaust-valve, a branch pipe connecting said cylinder at the side of said piston nearer said valve to the trainpipe, a valve in said branch pipe seated by pressure in said cylinder and a free branch pipe connecting said cylinder at the other side of said piston with the train-pipe, whereby said exhaust-valve is operated by variations of train-pipe pressure.

6. An auxiliary air-brake device comprising acylinder, apiston in said cylinder operatively connected to abrake-cylinder exhaust-valve, a branch pipe connecting said cylinder at the side of said piston nearer said valve to the trainpipe, a valve in said branch pipe seated by pressure in said cylinder, a free branch pipe connecting said cylinder at the other side of said piston with the train-pipe, whereby said exhaust -valve is operated by variations of train-pipe pressure and a valved relief-pipe also connecting the side of said cylinder nearer said exhaust-valve with the train-pipe.

- DENNIS DUNN.

Witnesses:

J AMES H. KRIOHNER, CARL BRANDAU. 

